In 8 May 1980, the World Health Organisation declared that “the world and its peoples have won freedom from smallpox.” Through decades of intense vaccination, this once fatal disease had been wiped out. It was a singular victory and having won it, countries around the world discontinued the vaccination programmes. After all, why protect against a disease that no longer exists (save in a few isolated stocks)?

Unfortunately, this is not a rhetorical question. The smallpox vaccine did more than protect against smallpox. It also reduced the risk of contracting a related illness called monkeypox, which produces the same combination of scabby bumps and fever. It’s milder than smallpox but it’s still a serious affliction. In Africa, where monkeypox originates from, it kills anywhere from 1-10% of those who are infected. And more and more people are becoming infected.

Anne Rimoin from the University of California, Los Angeles compared data on the virus in the Democratic Republic of Congo over the last three decades. She found that, during those years, monkeypox has become 20 times more common in humans. In one particular area, 72 people out of every million were infected each year between 1981 and 1986. Between 2005 and 2007, that figure rose to 1442 per million.

Rimoin thinks that we eased up the pressure on smallpox vaccination too soon. After victory was announced, the Global Commission for the Certification of Smallpox Eradication ruled that it wasn’t worth vaccinating people on the grounds of preventing monkeypox. However, it called for the disease to be closely monitored. Between 1981 and 1985, only 404 cases turned up in all of Africa, and simulations predicted that the disease was unlikely to spread too far in a human population before dying out. This was no public health threat. In 1986, even the monitoring programme was stopped.

Rimoin found that monkeypox was disproportionately affecting children and almost all of those who fell sick were born after 1980, when the smallpox vaccination programme was halted in the DRC. The vaccine wasn’t a perfect defence against monkeypox but it was still around 85% effective. Among people who were born during the vaccination era, those who were immunised were 5 times less likely to develop monkeypox than their protected peers. And this protection is clearly long-lasting; even 25 years on, they could still ward off the related virus.

These figures are probably underestimates too. The region’s inconsistent healthcare isn’t exactly conducive to accurate disease monitoring and Rimoin says that her team had word of many more cases, but couldn’t always check them out because of their remote location.

Monkeypox is spread by animals including squirrels and, fairly obviously, monkeys. As humans encroach upon the DRC’s tropical rainforests, the risk of being exposed to an infected carrier grows. Indeed, Rimoin found that the odds of contracting monkeypox were higher for people living near forested areas, and for men. As civil strife continues to affect the DRC, locals are being forced to rely more on hunting to get enough food and that brings men in close contact with furry viral reservoirs.

It’s an emerging threat, but Rimoin isn’t calling for smallpox vaccination to resume. Doing so would be logistically difficult in an area where even collecting data can be fraught. It might be better to take a more targeted approach, vaccinating only health workers who treat infected patients, and people who come into frequent contact with animal carriers. It may also be worth educating local people about the dangers of handling carrier species and the benefits of isolating people who show the very obvious symptoms, until they can be treated.

But most importantly, Rimoin wants active surveillance in regions where the virus circulates, especially since there are still so many unknowns about the virus. We need to better understand how it moves from human to human (and from animal to human), how often it’s fatal, or what the complications are.

It’s a good opportunity to take action now, at a time when the monkeypox is still confined to specific areas. Things might not stay that way. In 2003, there was a bizarre outbreak in the United States, as rodents from Ghana brought the disease to American prairie dogs, who handed it over to humans. All sorts of rodents the world over might become reservoirs for the disease and Rimoin writes, “If monkeypox were to become established in a wildlife reservoir outside Africa, the public health setback would be difficult to reverse.”

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5 thoughts on “Goodbye smallpox vaccination, hello monkeypox”

It gets on my nerves when I compare the situation in Africa with that in rich countries, where sometimes* even too much money is spent on disease prevention. Think of the swine flu pandemic – pharmaceutical companies are still filling their piggy banks. (swine, piggy, did you get it, ah ah ah! — ok, I need to get more social life). My point is: if a similar situation had taken place in Europe or Northern America, I doubt the not-so-effective** vaccination programme or at least the monitoring programme would have been stopped…
* I am among those who think that research funding is never too much… in theory; in practice of course there can be misuse and overuse of funds, and the swine flu case is an example. My consolation is that at least some young graduates had the opportunity to work…
** Although 85% seems not that bad at all to me

@ Martin: I believe that the money spent on pro active health care could be and should be criticised if one thinks it is not being spent well
Again, I am totally in favour of giving more funds to research (that’s one of the main reasons for which I’m leaving my home country – always cuts, cuts, cuts), including of course medical research. And I am totally in favour of following the precautionary principle in health care. What I wanted to lament is that, while in places like equatorial Africa too little efforts are made (i.e. too little money is spent) in preventing diseases and anticipating future scenarios, in rich countries even the opposite happens – that is, alarmism and disproportionate use of resources because of the interests of few. (Of course swine flu situations are an exception, and surely medical research is seldom overfunded. But when unjustified, dishonest alarmism takes place I think one should not avoid to point it out)

I agree with you more than disagree. The big problem is accessibility in these inhospitable areas. War undeveloped or destructed infrastructure would prevent even huge financial health care drives into these places. It is an awful problem.

We are lucky if we live in stable developed countries that can benefit easily from the latest developments in medicine. The rush to cut back on continued health monitoring of undeveloped or war compromised countries, supposedly for financial savings is tantamount to murder or it is playing with peoples lives. This is in the WHO and UN’s hands, and I doubt things will change much or at least not very fast.

We do take steps forward in eradicating these dreadful conditions, but I worry at how many steps back we keep taking!

“Smallpox, caused by the variola virus, is no longer found in the environment, but is considered a formidable biowarfare threat. SIGA’s novel countermeasure, ST-246®, works by blocking the ability of the virus to spread to other cells, preventing it from causing disease in laboratory testing to date, with no serious side effects reported. These clinical results support ST-246’s® use against smallpox and related orthopoxviruses for:

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Ed Yong is an award-winning British science writer. Not Exactly Rocket Science is his hub for talking about the awe-inspiring, beautiful and quirky world of science to as many people as possible.
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